The purpose of this project is to improve upon the assessment and treatment effectiveness of Antisocial Personality (ASP) disordered intravenous drug abusing (IVDA) opiate dependent patients. The development of more effective treatment methods for intravenous drug abusers has attained increased urgency given the recognition of this form of drug use as a major HIV transmission route. Psychiatric characterization studies of opiate dependent patients have revealed significant proportions with concurrent psychiatric disorders amenable to treatment. However, these studies consistently report that ASP is the second most frequently made concurrent psychiatric diagnosis. Unfortunately, the only thing we definitely know about the treatment of this cohort is that they are highly resistant to clinical interventions, generally difficult to manage, and are likely to evidence continuing patterns of intravenous drug use after entering treatment. Preliminary data has also recently linked ASP, opiate dependent patients to high rates of intravenous cocaine use. The present project will focus upon IVDA patients with ASP entering methadone treatment, a context that permits frequent contact and objective assessment of drug use behavior and treatment performance. In Study 1, we will determine the diagnostic profiles among newly admitted cocaine abusing and nonabusing opiate dependent patients, and begin further validation of a behaviorally anchored measure of current antisocial behaviors. In Study 2, these diagnostic measures will be related to treatment performance data in the further development of behavioral measures that are sensitive to identification and ongoing evaluation of patients with concurrent RDC and/or DSM-IIIR diagnoses of ASP. Study 3 will focus on an evaluation of a novel structured contingency management intervention for improving clinical outcome among patients with concurrent ASP. Overall, the results will contribute to more effective assessment and treatment of a significant subset of intravenous drug abusers, potentially reduce the spread of HIV transmission, and extend the validation of a new, and possibly more efficient, diagnostic instrument to an outpatient drug abuse population.